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 ###Instrução: Na Semana 13, quem foi o oponente?
 ###Tabelas: CREATE TABLE number_of_children_involved_in_ilo_categories_of_work_by_age_and_gender (number_of_children_involved_in_ilo_categories_of_work_by_age_and_gender_id AUTO_INCREMENT PRIMARY KEY, All Children ('000s) INT, Economically Active Children ('000s) INT, Economically Active Children (%) INT, Child Labour ('000s) INT, Child Labour (%) INT, Children In Hazardous Work ('000s) INT, Children In Hazardous Work (%) INT) CREATE TABLE returning_this_year_after_a_break_of_one_year_or_longer (returning_this_year_after_a_break_of_one_year_or_longer_id AUTO_INCREMENT PRIMARY KEY, Programme VARCHAR, Date(s) of original removal VARCHAR, Original channel(s) VARCHAR, Date of return VARCHAR, New channel(s) VARCHAR) CREATE TABLE schedule (schedule_id AUTO_INCREMENT PRIMARY KEY, Week INT, Date VARCHAR, Opponent VARCHAR, Result VARCHAR, Attendance INT) CREATE TABLE one_cent_test_tokens (one_cent_test_tokens_id AUTO_INCREMENT PRIMARY KEY, Year of Issue INT, Weight VARCHAR, Diameter VARCHAR, Thickness VARCHAR, Edge VARCHAR) CREATE TABLE former_districts (former_districts_id AUTO_INCREMENT PRIMARY KEY, District VARCHAR, Status VARCHAR, Date abolished VARCHAR, Former county VARCHAR, Successor VARCHAR)  
SELECT Opponent FROM schedule WHERE Week = 13